why are yawns contagious?

I don't know, maybe we should try asking.... Well I don't know is there a docta in the house woh knows wha? I like yawning in public though it is like a line in which everyone is taking turns at yawning, I yawn, you yawn, they yawn, we yawn!!!
Yaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaawn!!! Are you yawning now?

Yawns are social contagions. The first person who yawns gives tacit approval for everyone else in a group to do the same.

Lol, I just yawned when I read this. I'm not sure the scientific reason, but I think it has something to do with when you see it it triggers something in your brain. For example, when you see someone yawn your brain is reminded that the body needs a full puff of air or something so it makes you yawn.

I believe that is very true and have been proved scientifically (lol, I just yawned)
I don't know why though.
Here is some info though I found on google
http://www.howstuffworks.com/question572.htm

Haha, if I told I just yawned reading this, would you believe me??

lol..

=)

yes i think so because sometimes when you see someone throw up , then sometimes you throw up. Its very wierd, but i think that your brain is seeing the person yawning and says i have to do that to.

the reason we yawn is as a results of the fact our respiration slows inflicting a loss of oxygen and so we yawn to absorb a deep breath, it fairly is why we yawn as quickly as we are drained-our respiration slows down. And as quickly as we see somebody else yawn our respiration slows down slightly back so we yawn :)

it's a mark of a persons level of empathy. yawn in front of your friends and if they don't yawn then maybe they are not your friends. I yawned just reading this.
Sociopaths never yawn when others do because they are not connected to the people around them.

Thats a really good question. I once heard that yawning has to do with a build-up of nitrogen in the body. So maybe if your body is experiencing a build-up of nitrogen so are people around you. I'm not sure at all,but it kinda makes sense to me. Try the website below too.

You Yawn where there isn't enough oxygen to inhale and the person near you has the same condition thats why he yawns aswell!!!!!!!!!!!!!!!!!!